Media captionRupert Wingfield-Hayes in Seoul: There was a ''huge cheer'' at the beatification of 124 of South Korea's first Catholic martyrs

Pope Francis has celebrated a large open-air Mass to beatify 124 of South Korea's first Catholics at a ceremony in the capital Seoul.

He paid tribute to the Koreans, who died for their faith in the 18th and 19th Centuries.

Saturday's Mass came on the third day of his visit - his first trip to Asia since becoming pope in March 2013.

Pope Francis met survivors of the Sewol ferry disaster and delivered his first public Mass in the region on Friday.

The beatification ceremony was held at Gwanghwamun Square in central Seoul, with hundreds of thousands of people in attendance.

Beatification, or declaring a person "blessed", is the necessary prelude to full sainthood.

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The open-air ceremony is seen as the centrepiece of Pope Francis's trip to South Korea

Analysis by Rupert Wingfield-Hayes, Seoul:

There is something in the manner of Pope Francis that seems to win people over, Catholics and non-Catholics, wherever he goes. And he has done it again here in South Korea.

His lack of formality has shone through. On Friday he stopped in the middle of a prepared speech to a gathering of young Catholics and said he wanted to "speak directly from his heart, without reading from a piece of paper," but that his English was not good enough". "No!" shouted the 6,000 teenagers in one voice.

There is also plenty of talk, in this status-conscious society, about the Pope's use of a tiny hatch-back as his official car, most of it approving. The Church is seen in South Korea as a supporter of the poor and the politically dispossessed, so much so that the Korean right has accused it of being 'socialist'.

In South Korea Pope Francis seems to have found a Catholic clergy and believers who share his vision of what the Church of Rome should be.

'Spiritual desert'

The Pope is spending five days in South Korea, where the Catholic Church is growing. It currently has just over 5.4 million members, some 10.4% of the population.

Crowds of worshippers lined the streets leading up to Gwanghwamun Plaza for Saturday's ceremony. The square was the site where unrepentant Catholics were paraded before they were publicly executed.

"They were willing to make great sacrifices and let themselves be stripped of whatever kept them from Christ - possessions and land, prestige and honour - for they knew that Christ alone was their true treasure,'' Pope Francis told the crowd in his sermon.

"They challenge us to think about what, if anything, we ourselves would be willing to die for.''

This is a very significant and poignant moment for the Catholic Church in South Korea because the people who were beatified today were the founders of the church 200 years ago, says the BBC's Rupert Wingfield-Hayes in Seoul.

They were also unique because they were not converted by missionaries who came to Korea but they learnt about Catholicism themselves and brought the books back to Korea to spread the Catholic Church and were executed by the royal authorities for doing so, he adds.

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Pope Francis said the martyrs "knew the cost of discipleship" during his sermon on Saturday

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The Pope flew to a hilltop community which cares for the disabled

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The pope posed for selfies with young people at a seminar in Daejeon on Friday

Before Saturday's Mass got under way, he met some of the survivors and relatives of the South Korean ferry disaster that killed more than 300 people in April this year.

He was later greeted by a rapturous crowd of some 10,000 youths in Dangjin, where he spoke briefly off-the-cuff in English, acknowledging his difficulties with the language.

The Pope also flew southeast of Seoul to the hilltop Kkottongnae community established by a priest in the 1970s to look after sick and disabled Koreans. He stopped to pray there at a monument to aborted babies.

Meanwhile, China's leadership failed to receive a telegram sent by the Pope as he flew over the country on his way to South Korea, Vatican spokesman Federico Lombardi said on Friday.

It is traditional for the pontiff to send blessings to the leadership of a country he flies over, but this was the first time a pope had been permitted to use Chinese air space.

The gesture is seen as significant because the Vatican and China have had no formal ties since the Communist party took power in 1949.

A technical glitch was thought to have stopped the message from being received, which was later resent via the Italian embassy in Beijing, Mr Lombardi said.